The invention relates to a facsimile machine in which a document is scanned and the image of the document is converted into an electrical signal which is representative of the image. This electrical signal can then be stored, transmitted via telephone or radio wave, or processed in another manner. In a second or write mode the facsimile machine receives an electrical signal, such as for instance from a telephone line, and converts the electrical signal into a fixed copy of the image represented by such electrical signal. Such facsimile, or fax, machines typically output the copy on a medium such as paper. Typically, prior art designs used separate mechanisms for the read mode in which a light source is directed upon the document and a signal is produced by the reflected light from the document as it is detected by a photoelectric detector which typically would be a photoelectric cell or similar sensor. Separate apparatus within the machine is used when an image signal is received by the fax machine to convert that image signal into an actual fixed copy. Such conversion has been done using thermal paper and photographic means. More recently fax machines have used a scanning laser head to place a photo image on a photo receptor device such as an electro-static drum copier. Such laser heads are relatively large and expensive, and in many instances require complicated scanning mirrors. Both thermal printing heads and scanned laser printing heads are slow and often require that the signal to be processed must be stored as it is received from a transmission line.
Thin film electroluminescent line array emitters and printers using such are known. An example of this type of application is disclosed in U.S. Pat. No. 4,535,341 to Kun et al. U.S. Pat. No. 4,535,341 is incorporated herein by reference. Other examples of thin film electroluminescent devices being used in printers are shown in U S Pat. Nos. 4,734,723 and 4,807,047.
In our co-pending United States patent application Ser. No. 527,213 which issued as U.S. Pat. No. 5,025,321 on Jun. 18, 1991 we disclose a facsimile machine which uses a thin film electroluminescent device to provide the photo-imaging source to a photoreceptor in the write mode, and also to provide the source for illuminating the paper when a scanning sensor is used in the reading mode. In that disclosure we teach that the electroluminescent device should be pivoted to cause the emitted light to travel across the page and then reflect to a sensor containing an array of photo cells containing as many as 2500 individual photo cells. Such large arrays are expensive.